Project Summary/Abstract Mammals rely heavily on their olfactory systems for survival and reproduction. The accessory olfactory system (AOS), best known for its role in pheromone processing, is a dedicated system for the detection of non-volatile social chemosignals. Such social chemosignals are thought to help identify conspecifics and heterospecifics, as well as convey information about the physiological state of other animals. Interestingly, the accessory olfactory bulb (AOB), the first and only dedicated circuit in the AOS, has been shown to change how it processes social stimuli after experience. However, the mechanisms by which experience induces this plasticity are not well understood. The overall goal of this project is to better understand how experience can shape neural circuits. The proposed research will utilize electrophysiology to first identify physiological changes in interneurons induced by repeated experience. In addition, single cell RNA sequencing will be used to identify activity- dependent changes in gene expression. Finally, chemogenetic strategies will be used to manipulate the interneuron populations that undergo plasticity to determine if they play a direct role in behavioral output. By identifying changes in the physiology and gene expression of AOB interneurons, and determining their behavioral role after repeated social experience, this work will help identify the mechanisms involved in the central processing of chemosensory information and determine the contributions of interneurons to mammalian social behavior.